LOANS HELD FOR INVESTMENT - Portfolio Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in the activity of loan portfolio
Balance at the beginning of the period	$ 1,524,873	$ 1,726,283
Initial funding	493,913	510,529
Origination fees and discounts, net of costs	(7,539)	(5,816)
Additional funding	185,281	33,693
Amortizing payments	0	(645)
Loan payoffs	(482,407)	(746,120)
Loan converted to real estate owned	(38,636)
Origination fee accretion	7,013	6,949	$ 6,578
Balance at the end of the period	$ 1,682,498	$ 1,524,873	$ 1,726,283